the difference between generators and iterators in Python (code is tested under Python3.5):
num01–> iterator
Definition:
For container objects such as list, string, tuple, dict, and so on, it is convenient to use a For loop traversal. Invoke the ITER () function on the container object in the background for statement. ITER () is a Python built-in function.The ITER () function returns an iterator object that defines the next () method, which accesse
Welcome to the wonderful flow control world. Python 2.2 (now the third edition of the Alpha release-see resources later in this article) will give programmers some new options that are not available in earlier Python versions--or at least not very convenient.
While the Python 2.2 gives us less understanding than complete continuity and stackless in Python, it can be said that the behavior of generators and iterators is somewhat different from traditi
Python iterators and generators
First of all, the iterator, for the string, list, dict, tuple and other such container objects, using for loop traversal is very convenient. In the background for statement to call the ITER () function on the container object, ITER () is a python built-in function. ITER () returns an iterator object that defines the next () method, which accesses the container element individually, and next () is a python built
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increased by one. The generator continues the while loop and comes back to the yield statement ...When you call the generator function, it returns a generator object. If you pass this object to the Dir () function, you will find the __iter__ and __next__ two method names in the returned results.We typically use generators for lazy evaluation. Using generators in this way is a good way to handle big data. I
New features of Php5.5 Generators in ** PHP5.5.0 **, the generator * (Generators) * feature is added to simplify implementation of the Iterator interface * (Iterator) * complexity of creating a simple iterator.
Through the generator, we can easily use foreach to iterate a series of data without having to build the objects to be iterated in the memory in advance, greatly reducing the memory overhead.
When
Comparison of four Jad generators (download with generator)
Due to the large number of games uploaded, it is inevitable that sometimes the JAD file of the game will go wrong. In this case, you need to re-generate a JAD file yourself. However, many online players will not use the Jad generator, now I will write a brief description for your reference.I now have four Jad generators: jadmaker, jadcreat
I often talk about Python decorators, iterators, and generators.
When learning python, the three major "namespaces" are a small difficulty for people without programming experience in other languages, this blog explains how to understand the decorator, iterator, and generator.
Why do I need a decorator?
What is a decoration device? "Decoration" literally refers to the act of beautifying the buildings according to certain ideas and styles. The so-calle
The generators and iterators in Python are easy to use, but the characteristics of the generators and iterators are not quite in place, and today the knowledge is collated.IteratorsTo better understand iterators and builds, we need to briefly review the concept of the iterator protocol.Iterator protocol1. An iterator protocol means that an object must provide a next method that either returns the next item
1. For loop in Python for inch [1,2,3,4]: 2. Iterative and iterative protocolsiterable: An iterative, repeatable, iterativeIterative: In general, it can be used for loops, such as String (str), list, tuple (tuple), dictionary (Dict), collection (set), range, map, filter, enumerate, and so on.Iterative---iterators: remove elements from a data setThe definition of an iterative protocol: The _iter_ method is implemented internallyCan be iterated for the for loop, there must be a _iter_ method i
Python functions: iterators and generatorsIterators and generators are one of the key points in a function, so be sure to know what the iteration is. What is an iterator?Preview:Process the file, the user specifies the file and the content to find, and prints the file with each row that contains the content you want to find to the screen (using the builder)One, iterator650) this.width=650; "src="/img/fz.gif "alt=" Copy Code "style=" Margin:0px;padding
The features of the generator and iterators are described in 1. Generator (generator) 1. Assignment Generator 1. Create方法:x = (variable for variable in iterable)例如:x = (i for i in range(10)) print(x) >>> 2. Call方法:x.__next__()返回值:object#对应生成器一般使用该种方法调用,当然也可以通过for循环进行遍历。2. Function BuilderFunction generators are also commonly used or commonly said generators, as the name implies is created by the functio
Object iterable can be iteratedAn object that can act directly on a for loop is called an iterative object.There are data types such as list, dict, tuple, set, str, and generator (including generators and generator function with yield). Includes ordered and unordered objects.To determine whether an object is a Iterable object. Here's how:
From collections Import iterable
Isinstance ([],iterable)
Iterator iteratorIterations, that is,
One, generators and generators1, List-generatedMyList = [I*i for I in range (3) if i>1]print (mylist) run Result: [4]You can find that the expression for the quick list is generated, for loop range (3), and if I is greater than 1, multiply it by yourself and then output.2, generatorMygenerator = (i*i for I in range (3)) print (mygenerator) Run Result: You can see that this generator and the list generation are very s
: Executes next (iter_dic), assigns the resulting value to K, and then executes the Loop body code3: Repeat the process 2 until the exception stopiteration is caught, ending the loopfeatures of the five iterators# Advantages: - provides a unified, index-independent iterative approach - lazy computing, saving memory # Disadvantages: -Unable to get length ( Only when the next is finished will you know how many values are there)-you can only walk back and not go backwards.Generator Life
]! '%(baozi,name))7 8 defproducer (name):9A = consumer ('A')Tenb = Consumer ('B') OneA.__next__() AB.__next__() - Print('Get ready to make buns.') - forIinchRange (1,11): theTime.sleep (1) - Print('made 2 buns.') - a.send (i) - b.send (i) + -Producer'ABC')implementing concurrent parallel operations with generatorsSecond, iteratorswe already know that there are several types of data that can be directly applied to a for loop:A class is a collection of data types, such as list, t
default execution is done to the function, and if a return is encountered, the stopiteration terminating iteration is thrown directly.Code 5 File Readdef read_file (Fpath): block_size = 1024x768 with open (Fpath, ' RB ') as F: While True: BLOCK = F.read (block_ SIZE) if block: yield block else: returnCalling the Read () method directly on a file object causes unpredictable memory consumption. A good approach is
=show_2 () show_p.__next__() show_p.__next__() show_p.send (10)#incoming Ten# analog Range () def Lrange (m=0,n,l=1): count=m while Count N: yield Count + = L for in Lrange (2,10,2) :print(i)Asynchronous serialAdorner (decorator):Decorator principle:There are a few things you can do when @w1:1, execute W1 ()2, the modified function show passed to the W1 parameter3, the adorner must have a return value, return value in order to encapsulate the original show function into
method: Returns the next element of the iteratorA = {2,3,4,}b = iter (a) print (b.__next__ ()) print (b.__next__ ()) print (b.__next__ ()) print (b.__next__ ()) out : 234Traceback (most recent): File "practice3.py", line 216, in Ps: As can be seen from the above example, the elements in the iterator are accessed, and if you call the __next__ method again, you will be prompted stopiteration2) __iter__ method: Returns the Iterator object itselfA = {2,3,4,}b = iter (a) print (b.__iter__ ()) Out:
sequence to illustrate the difference between a generator and a normal function.Common function implementationdef fib (max): = 0, 0, 1 = [] while n Max: res.append (b) = B, a + b = n + 1 return= fib (6)print(res) for inch Res: Print (i) results of implementation [1, 1, 2, 3, 5, 8]138Generatordef fib2 (max): = 0, 0, 1 while n Max: yield b = b, A + b = n + 1
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